Boric-acid-alkylolamine reaction product



United States Patent Ofilice 3,227,739 Patented Jan. 4, 1966 The present invention relates to new additives and to improved lubricating oil compositions containing these additives. In particular, it relates to additives formed by reacting certain aminetype compounds with boric acid.

The additives of the present invention are effective as rust inhibitors and, in addition, minimize copper-lead bearing corrosion Certain prior art inhibitors, though very effective in preventing rust, cannot be used in some applications because of their adverse copper-lead bearing corrosin characteristics. Included in the prior art compounds, which are excellent antirust additives, are amine type compounds such as amines, hydroxy amines, amino alcohols, and the like. These amine-type compounds exhibit copper-lead bearing corroding tendencies which preclude their use in many applications.

It is an object of this invention to provide an effective antirust additive which, in addition, does not corrode copper-lead bearings. It is an object of this invention to provide lubricating oil compositions containing these improved additives. In the present invention it has been found that solving the problem of copper-lead bearing corrosion involves more than merely neutralizing a rust inhibitor with some type of acid. It has been found that the neutralization in order to be effective must be accomplished by the use of boric acid. As a preferred embodiment of the present invention, it has been found that certain critical concentrations of the boric acid adduct in a lubricating oil result in an unexpectedly superior lubricating oil composition.

The compounds of the present invention are represented by the following general formula:

(CH2)nO where n is an integer from 2 to 3 and R is a C to C alkyl group.

In preparing the amine-type compounds suitable for use in the present invention, about equal molar proportions of diethanolamine or dipropanolamine and a longchain, 1,2-epoxide' are reacted, under a nitrogen atmosphere, at a temperature in the range of 25 C. to 250 C. for a period of about 15 minutes to hours. Preferably, a temperature of 110 C. and a reaction time of about 2 hours are used. Unreacted starting materials are removed by vacuum distillation.

The 1,2-epoxides will contain from about 8 to 26 carbon atoms. These epoxides are described in FMC Corporation Technical Bulletins, Nos. 72, 73 and 74.

The compounds of the present invention are prepared by reacting the above-described amine-type compound with boric acid. A temperature in the range of about 200 F. to 400 F., preferably 300 F., is used. In general, equal molar proportions of reactants are used.

The present invention will be further understood by the following examples.

EXAMPLE 1 N,N-diethanol Z-hydroxy G -C amine, which is an antirust additive, was prepared as follows:

Commercially available C C epoxide (made from animal-derived olefin and hydrogen peroxide) was used.

gm. of diethanolamine were placed in a one-liter flask equipped with stirrer, condenser, thermometer and dropping funnel. The amine was heated to C. and then 273 gm. of the epoxide added dropwise over one hour. Stirring was continued for 2 hours at 110 C. and the product, Additive A, cooled (solid at room temperature) An additive of the present invention was prepared by reacting an oil solution of Additive A with boric acid.

EXAMPLE 2 100 gm. of the product of Example 1 were placed in a 400 ml. beaker together with 16.2 gm. of boric' acid. Heating and stirring were performed until a temperature of 300 F. was reached. The product, Additive B, lost 13.7 gm. weight in the form of vapor (vigorous evolution) and as a result of normal losses on stirrer and thermometer (estimated at 1 to 2 gm.).

Additive B, prepared above, was added to a lubricating oil and tested for its copper-lead bearing corrosion properties. In this test, Additives A and B were com pared with lubricating oils containing N,N-diethanol 2- hydroxy O -C amine neutralized with other acids. This test consists of operating, under control conditions, engines containing different crankcase oils and determining the resulting loss in weight of connecting rod bearmgs.

The results of this test are shown below:

1 Base oil was a. fully formulated SAE 10W-30 motor oil. 2 C35 dimer acid commercially available from Emery Industries Inc. as Empol 1022.

The above results show that the advantage of the boric acid adduct of the present invention is not simply a matter of neutralization but is specific to boric acid.

In order to determine the antirust properties of the present invention, the following test was performed.

RUST TEST The test is a very severe test designed to predict rusting of hydraulic valve lifters. In this test new 1958 Oldsmobile valve lifters (cast iron containing a small amount of nickel) are disassembled into body and plunger. These pieces are degreased with solvent and are then allowed to dry, 10 grams of test oil are diluted to 100 grams with hexane. Clean and dry test pieces are soaked in a test solution for one hour, removed and air dried for 30 minutes. This leaves a very thin test oil film on the test pieces. An agar gel collar is cast over the bottom half of each of the two lifter pieces. This collar promotes corrosion by masking half of each lifter piece from oxygen available during the test, i.e. it sets up an oxygen concentration cell. The coated pieces are then covered with water which is aerated and held at 110 F. for 20 hours. Both the Water and the agar gel contain BaCl-2H O for added severity. The pieces show rust in two areas. Red rust appears above the agar (exposed to oxygen-rich Water) and black rust under the agar (exposed -to oxygen-poor water). The two areas are rated for per cent area covered with rust and the ratings for the two areas are averaged. In the test bath, pieces coated with a noninhibited motor oil are carried along as an internal standard to compensate for minor variations in bath conditions. The final rating compares the inhibited test oil to the noninhibited standard as follows: the rust area of the pieces coated with test oil is subtracted from the rusted area of the pieces coated with the standard. The number obtained is divided by the rusted area of the standard and multiplied by 100 to yield the percent improvement over the standard. Thus, the maximum value obtainable is 100% (perfectly clean), while demonstrated equivalence to the standard and negative values indicate promotion of rust.

The results of this test are shown below:

Table II Percent advantage Additive in base oil: over base oil 1.0 wt. percent Additive A 82 1.0 wt. percent Additive B 83 The above results show that the rust inhibition properties of Additive A are maintained after preparation of the boric acid adduct (Additive B).

The mole ratio of boric acid to the amine-type compound aifects the rust inhibition properties of a lubricating oil composition containing the adduct as shown below:

1 Base oil was a fully formulated SAE W-30 motor oil. 2 Glassy, inhomogeneous solids.

The above results show that the boric acid neutralization produces optimum results at a 1/1 molar ratio.

The eifect upon rust inhibition of the boric acid adduct concentration is shown below:

Table IV Concentration, wt. percent Additive A in base oil Percent advantage over base oil Base oil was fully formulated SAE 10W-30 motor oil.

The results show that the optimum balance between rust inhibition and concentration is obtained at a boric acid adduct concentration of about 0.5 wt. percent.

The additives of the present invention may be added to lubricating oils in a concentration range of from about 0.02 to 5.0 wt. percent. The preferred concentration range is about 0.10 to 1.0 wt. percent. An especially preferred concentration is about 0.5 Wt. percent. Various mineral and synthetic lubricating oil base stocks may be employed. The base stock may be any suitable oil of lubricating viscosity grade, including straight mineral oil fractions or distillates derived from the ordinary parafiinic, naphthenic, asphaltic or mixed base crude oils by the usual refining methods including solvent extraction, treatment with acid, alkali, clay, aluminum chloride, and the like, hydrogenation treatment, and so on. Synthetic oils may be of the hydrocarbon type or they may be of the ester type such as di-Z-ethyl hexyl sebacate, C oxo acid diesters of tetraethylene glycol, etc.

The additives of the invention may be employed in lubricants in conjunction with other additives such as detergent type additives, e.g. metal organic sulfonates, metal alkyl phenol sulfides, etc., pour point depressants, dyes, antioxidants, and the like.

While several applications have been shown for the products of the present invention, it is not intended that these examples limit or restrict the invention in any respect.

What is claimed is:

1. A composition of matter having the general formula:

where n is an integer from 2 to 3 and R is a C to C alkyl group.

2. A composition of matter having the formula:

H CHzCHzO I RC-ON I OH H OHz-OH2O where R is a C -C alkyl group.

3. A composition of matter having the formula:

H II OHz-CIIz-CH2O R-(J(|]N/ BOH 11 CHzCHzCHz-O where R is a C to C alkyl group.

References Cited by the Examiner UNITED STATES PATENTS 2,942,021 6/1960 Groszos et al 260-462 2,970,130 1/1961 Finestone 260462 XR 3,014,870 12/1961 Reynolds et a1 25249.6 3,106,573 10/1963 Bamford 260462 3,125,528 3/1964 Kay et al 25249.6

CHARLES B. PARKER, Primary Examiner.

DANIEL E. WYMAN, Examiner. 

1. A COMPOSITION OF MATTER HAVING THE GENERAL FORMULA: 